Hi
My 38120S 10Ah are coded JI03 and JI04. The first box contain a warning paper about too long screw they push on rupture disc.

And after many weeks of search and design about limited slip drive train I finaly concluded that will be realy complex and costly to build a custom direct drive lsd drive train. It's easy in a motorcycle or a go-kart, but it's another way in a car.
So now, the best way I find is use a Sentra SE-R Spec-V transmission. They come stock with a helical lsd (Torsen) and have 6 speeds.
I think use the 4e and 5e gears to have a 4.378 and 3.345 ratio. I can get one at scrap yard for 300$.
After some calculs, that give me the same 0-60 mph time than direct drive set-up cause by the 0.5s shifting delay. So a faster 0-45 mph, same 0-60 mph and a faster 0-75 mph and 1/4 miles.

I'm a bit disapointed to don't go direct drive, but I know it will be probably a bit more efficient and a lot less complex. So it's not bad.... I think!

The small 800cc CDI diesel motor is out of the frame. It haven't a lot of place for a big 11" motor and a Nissan transmission.....
The ICE is put at 45° in the rear of the Smart and pass over the drive shafts. So, replace it for a big 11" cylinder will be not easy!!

I have been thinking about the reverse gear issue - for a lightweight 2 seater

(1) -No reverse just push it back
(2) - Use the reversing contactor I got from an old forklift - should never be actuated under load
(3) - use two double Alderson connectors to reverse the field coils
unplug the green ones plug in the red ones!
(4) - Lotus 7 type cars with motorbike engines use a starter motor to drive the car backwards

I have another idea to put on the table about reversing motor rotation in a direct drive application.....

What do you think about add another small controller to the motor? I have a 156v 1000A controller to go forward and I think about a cheap (100$) 12v 200A controller to go in reverse!

This configuration have the the important advantage than no power is lost in the reversing contactor. Why lose 100% of the time 0.5% of your power in the contactor (even more in stop and go in the city traffic when motor often see 1000A) when you only need this contactor to go in reverse 0.5% of time during a ride?

I only need a good auxiliary battery coupled with the DC-DC. 200A is less than an engine starter need during some sec.Or, if that exist, I need a small 156v 200A controller!In fact, I'm not persuaded I need 200A to go in reverse at 5 mph during 5-10 sec.

Sounds like a good alternative to me, in fact I might just do the same myself. It means a small weight penalty, and a little more complexity, but like you say it eliminates voltage drop across the reversing contactors. With a car that is as short as your Smart (and my Mini) it's not as if we'll need to reverse very often You might want to avoid parking facing down a steep hill though, just in case someone parks right in front of you...

Were you thinking of using the same throttle potentiometer for both controllers?

I have another idea to put on the table about reversing motor rotation in a direct drive application.....

What do you think about add another small controller to the motor? .....What do you think about this solution to go in reverse?

Hi Yab,

I don't see it How do you connect a second controller to a series motor and get reverse? You still have to reverse the field respective to the armature. And once you do that, just use you main controller.